/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_scale_q15.c
 * Description:  Multiplies a Q15 vector by a scalar
 *
 * $Date:        23 April 2021
 * $Revision:    V1.9.0
 *
 * Target Processor: Cortex-M and Cortex-A cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "dsp/basic_math_functions.h"

/**
  @ingroup groupMath
 */

/**
  @addtogroup BasicScale
  @{
 */

/**
  @brief         Multiplies a Q15 vector by a scalar.
  @param[in]     pSrc       points to the input vector
  @param[in]     scaleFract fractional portion of the scale value
  @param[in]     shift      number of bits to shift the result by
  @param[out]    pDst       points to the output vector
  @param[in]     blockSize  number of samples in each vector
  @return        none

  @par           Scaling and Overflow Behavior
                   The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.
                   These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
 */

#if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)

#include "arm_helium_utils.h"

void arm_scale_q15(
    const q15_t *pSrc,
    q15_t scaleFract,
    int8_t shift,
    q15_t *pDst,
    uint32_t blockSize)
{
    uint32_t blkCnt; /* loop counters */
    q15x8_t vecSrc;
    q15x8_t vecDst;
    q31x4_t low, high;

    /* Compute 8 outputs at a time */
    blkCnt = blockSize >> 3;

    while (blkCnt > 0U) {
        /*
         * C = A * scale
         * Scale the input and then store the result in the destination buffer.
         */
        vecSrc = vld1q(pSrc);
        low    = vmullbq_int(vecSrc, vdupq_n_s16(scaleFract));
        low    = vqshlq_r(low, shift);
        vecDst = vqshrnbq_n_s32(vecDst, low, 15);

        high   = vmulltq_int(vecSrc, vdupq_n_s16(scaleFract));
        high   = vqshlq_r(high, shift);
        vecDst = vqshrntq_n_s32(vecDst, high, 15);

        vst1q(pDst, vecDst);
        /*
         * Decrement the blockSize loop counter
         */
        blkCnt--;
        /*
         * advance vector source and destination pointers
         */
        pSrc += 8;
        pDst += 8;
    }
    /*
     * tail
     */
    blkCnt = blockSize & 7;
    if (blkCnt > 0U) {
        mve_pred16_t p0 = vctp16q(blkCnt);
        vecSrc          = vld1q(pSrc);
        low             = vmullbq_int(vecSrc, vdupq_n_s16(scaleFract));
        low             = vqshlq_r(low, shift);
        vecDst          = vqshrnbq_n_s32(vecDst, low, 15);

        high   = vmulltq_int(vecSrc, vdupq_n_s16(scaleFract));
        high   = vqshlq_r(high, shift);
        vecDst = vqshrntq_n_s32(vecDst, high, 15);
        vstrhq_p(pDst, vecDst, p0);
    }
}

#else
void arm_scale_q15(
    const q15_t *pSrc,
    q15_t scaleFract,
    int8_t shift,
    q15_t *pDst,
    uint32_t blockSize)
{
    uint32_t blkCnt;            /* Loop counter */
    int8_t kShift = 15 - shift; /* Shift to apply after scaling */

#if defined(ARM_MATH_LOOPUNROLL)
#if defined(ARM_MATH_DSP)
    q31_t inA1, inA2;
    q31_t out1, out2, out3, out4; /* Temporary output variables */
    q15_t in1, in2, in3, in4;     /* Temporary input variables */
#endif
#endif

#if defined(ARM_MATH_LOOPUNROLL)

    /* Loop unrolling: Compute 4 outputs at a time */
    blkCnt = blockSize >> 2U;

    while (blkCnt > 0U) {
        /* C = A * scale */

#if defined(ARM_MATH_DSP)
        /* read 2 times 2 samples at a time from source */
        inA1 = read_q15x2_ia(&pSrc);
        inA2 = read_q15x2_ia(&pSrc);

        /* Scale inputs and store result in temporary variables
         * in single cycle by packing the outputs */
        out1 = (q31_t)((q15_t)(inA1 >> 16) * scaleFract);
        out2 = (q31_t)((q15_t)(inA1)*scaleFract);
        out3 = (q31_t)((q15_t)(inA2 >> 16) * scaleFract);
        out4 = (q31_t)((q15_t)(inA2)*scaleFract);

        /* apply shifting */
        out1 = out1 >> kShift;
        out2 = out2 >> kShift;
        out3 = out3 >> kShift;
        out4 = out4 >> kShift;

        /* saturate the output */
        in1 = (q15_t)(__SSAT(out1, 16));
        in2 = (q15_t)(__SSAT(out2, 16));
        in3 = (q15_t)(__SSAT(out3, 16));
        in4 = (q15_t)(__SSAT(out4, 16));

        /* store result to destination */
        write_q15x2_ia(&pDst, __PKHBT(in2, in1, 16));
        write_q15x2_ia(&pDst, __PKHBT(in4, in3, 16));
#else
        *pDst++ = (q15_t)(__SSAT(((q31_t)*pSrc++ * scaleFract) >> kShift, 16));
        *pDst++ = (q15_t)(__SSAT(((q31_t)*pSrc++ * scaleFract) >> kShift, 16));
        *pDst++ = (q15_t)(__SSAT(((q31_t)*pSrc++ * scaleFract) >> kShift, 16));
        *pDst++ = (q15_t)(__SSAT(((q31_t)*pSrc++ * scaleFract) >> kShift, 16));
#endif

        /* Decrement loop counter */
        blkCnt--;
    }

    /* Loop unrolling: Compute remaining outputs */
    blkCnt = blockSize % 0x4U;

#else

    /* Initialize blkCnt with number of samples */
    blkCnt = blockSize;

#endif /* #if defined (ARM_MATH_LOOPUNROLL) */

    while (blkCnt > 0U) {
        /* C = A * scale */

        /* Scale input and store result in destination buffer. */
        *pDst++ = (q15_t)(__SSAT(((q31_t)*pSrc++ * scaleFract) >> kShift, 16));

        /* Decrement loop counter */
        blkCnt--;
    }
}
#endif /* defined(ARM_MATH_MVEI) */

/**
  @} end of BasicScale group
 */
